More responsive key input

Use biased select!, don't eagerly process lsp message since we want to
prioritize user input rather than lsp messages, but still limit rendering
for lsp messages.

helix-term/src/application.rs

@@ -9,6 +9,7 @@ use log::error;
 use std::{
     io::{stdout, Write},
     sync::Arc,
+    time::{Duration, Instant},
 };
 
 use anyhow::Error;
@@ -130,6 +131,8 @@ impl Application {
 
     pub async fn event_loop(&mut self) {
         let mut reader = EventStream::new();
+        let mut last_render = Instant::now();
+        let deadline = Duration::from_secs(1) / 60;
 
         self.render();
 
@@ -139,26 +142,22 @@ impl Application {
                 break;
             }
 
-            use futures_util::{FutureExt, StreamExt};
+            use futures_util::StreamExt;
 
             tokio::select! {
+                biased;
+
                 event = reader.next() => {
                     self.handle_terminal_events(event)
                 }
                 Some((id, call)) = self.editor.language_servers.incoming.next() => {
                     self.handle_language_server_message(call, id).await;
-
-                    // eagerly process any other available notifications/calls
-                    let now = std::time::Instant::now();
-                    let deadline = std::time::Duration::from_millis(10);
-                    while let Some(Some((id, call))) = self.editor.language_servers.incoming.next().now_or_never() {
-                       self.handle_language_server_message(call, id).await;
-
-                       if now.elapsed() > deadline { // use a deadline so we don't block too long
-                           break;
-                       }
-                    }
+                    // limit render calls for fast language server messages
+                    let last = self.editor.language_servers.incoming.is_empty();
+                    if last || last_render.elapsed() > deadline {
                         self.render();
+                        last_render = Instant::now();
+                    }
                 }
                 Some(callback) = self.jobs.futures.next() => {
                     self.jobs.handle_callback(&mut self.editor, &mut self.compositor, callback);